True north changes throughout time, but magnetic north is stable in one place. Moreover, true north is a fixed place on the Earth whereas magnetic north is the direction in which the compass needle points in. Grid north is a term similar to these two. Map users need to understand these three types of the north. In this article, you can check about the grid north.
Definition of grid north
The grid north is a navigational phrase used to refer to the northward on a grid line in a map projection. The grid north differentiates the true north and magnetic north in that it is aligned to grid lines and always points upwards on a map. The grid lines from the grid north subdivide the UK into squares one kilometre, east of the Atlantic ocean's imaginary point. The line points towards the grid north and has a slight variation from the true north. Some navigators ignore the difference between grid north and true north because of the slight differences.